ABSTRACT

Vascular tonus has been controlled by several factors secreted from endothelium in physiological conditions. In the present study, the possible changes on endothelium-derived contractile responses in normoglycemic and hyperglycemic conditions in terms of exposure-time dependency has been investigated.

To assess the possible alterations under acute hyperglycemia with different incubation periods on endothelium-derived contractile responses in isolated rat thoracic aorta, A23187-mediated contractile responses were performed in a cumulative manner for isometric tension measurements.

Incubation for 3 hours with Krebs solution containing high glucose increased the A23187-mediated contraction of rat thoracic aorta. The A23187- induced contraction significantly decreased in response to the same incubation period with normoglycemic conditions and totally abolished with incubation for 6 hours. The possible effects of osmotic pressure induced by high glucose content checked with mannitol.

Our results indicated that the A23187-mediated contractile response was increased by acute hyperglycemia. These data has shown the detrimental effects of short term hyperglycemia on endothelium-derived contractile factors. Also the incubation period-related characteristics of A23187-mediated contractile responses as observed in normoglycemic conditions indicate the unstable properties of endothelium-derived contractile factors and/or related signaling pathway(s).